INTRODUCTION We are very pleased reviewers felt that "this was a very impressive imaging core" and we have "a highly experienced and qualified team" with "a clear track record of accomplishments." We are grateful that the reviewers recognized us "as one of the leading DTI groups in the world" and our "expertise in animal imaging and the development and/or refinement of DTI pulse sequences are clear strengths." The primary concern of the reviewers was raised in Project-1 and has been addressed in great details in the revised project -1. We hope that the reviewers will agree that we have made significant improvement in our presentation in Proejct-1. Only minor changes have been made in the description of Core C, mainly materials directly related to the previously proposed Project-1.